Rolling mill control system



Dec. 17, 1968 C. DEY ET AL 3,416,341

ROLLING MILL CONTROL SYSTEM Filed Dec. 12, 1966 2 Sheets-Shet 1IINVENLTORS QL CHESTER DEY 72 50 56 52 A. DEAN SMITH Dec. 17, 1968 c.DEY ETAL 3,416,341

ROLLING MILL CONTROL SYSTEM Filed Dec. 12, 1966 2 Sheets-Sheet 2INVENTORS CHESTER DEY BY A. DEAN SMITH United States Patent 3,416,341ROLLING MILL CONTROL SYSTEM Chester Dey, Piedmont, and Arthur DeanSmith, San

Lorenzo, Calif, assignors to Kaiser Aluminum &

Chemical Corporation, Oakland, Calif., a corporation of Delaware FiledDec. 12, 1966, Ser. No. 600,928 17 Claims. (Cl. 72-20) The inventionrelates to rolling mills and more particularly to an improved roll gapcontrol system therefor wherein the functions of a rolling mill pushupcontrol means and a rolling mill roll bending control means are bothfully integrated with each other during operation of the rolling milland wherein the pushup means are also operated in an improved fashion sothat the material being rolled will maintain a substantially uniformgauge across its entire width irrespective of changes in various millload conditions which occur during rolling.

In prior rolling mill practices, in order to maintain substantiallyuniform gauge across the entire width of the material being rolled, ithas been customary to use work or backup roll bending devices and rollpushup devices. The bending devices apply bending loads to the workrolls to counter or compensate for deflection of certain portions of therolls due, for example, to separating forces exerted upon the rolls bythe workpiece, roll heat up, roll flattening, etc. Roll pushup devices,such as pushup cylinders, are used in addition to the normal roll screwdown devices primarily to compensate for stretching of the mill housingor frame, which also normally occurs as a result of the separatingforces exerted directly upon the work rolls and indirectly on the millframe by the material, such as metal sheet, that is rolled. Despite allof these corrective measures, problems still exist because of thefailures that have occurred to date in efliciently and reliablyintegrating the control system for the roll bending devices with thecontrol system for the pushup devices whereby each control system willstill perform its assigned function, as such, while at the same timetaking into account and at the same time synchronizing its operationswith those of its companion control system so that the desired optimumroll gap setting for the mill is constantly maintained throughoutrolling.

Accordingly, it is a primary purpose of the instant invention toprovide, among other things, an improved and highly reliable controlarrangement for operating and integrating a mill roll bending devicewith a mill roll pushup device, whereby each device will eflicientlyperform its own assigned function, as such, while at the same time beingfully synchronized with its companion device whereby one device will notonly not adversely affect the operation of the other device, but insteadwill advantageously complement the workings of the other device inmaintaining the desired optimum roll gap setting for a given rollingoperation.

This and other purposes and advantages of the instant invention willbecome more apparent from a review of the following detailed descriptionwhen taken in conjunction with the appended drawings, wherein:

FIG. 1 is a side elevational view of a typical rolling mill with certainparts removed and other parts broken away and incorporating the improvedintegrated control systems of the instant invention;

FIG. 2 is a sectional view generally taken along line 22 of FIG. 1 withparts of the mill being removed and with other parts being schematicallyshown for purposes of illustration and with the integrated mill controlsystems of the instant invention being schematically added to illustratethe novel details thereof; and

FIG, 3 is a diagrammatic view of a modified form of the integratedcontrol systems of FIG. 2.

3,416,341 Patented Dec. 17, 1968 With further reference to the drawingsand in particular FIGS. 1 and 2, a preferred form of apparatus that canbe used in carrying out the teachings of the instant invention generallycomprises a typical four-high rolling mill stand 10 used to roll ferrousor non-ferrous metals. Mill stand 10 includes a mill housing orframework 12, a pair of backup rolls 14 and a pair of work rolls 16.Although the forming surfaces of the work rolls 16 along their axiallengths are shown to have a uniform diameter, these surfaces can, ifdesired, be initially made to have an axial convex or concave shape inaccordance with customary roll finishing practices. Rolls 14 and 16 arerotatably and adjustably mounted within the framework 12 by the journalor reduced ends of rolls 14 and 16 being appropriately mounted in theirrespective chock blocks 26 and 28 and these chock blocks 26 and 28 arethen slidably mounted within vertically recessed track means in thewindow 13 of the housing 12 in the usual fashion as indicated by thedotted lines in FIG. 1. It is to be understood, of course, although notshown, that the customary jack rams such as those shown in United StatesPatent 2,903,926 to R, M. Reichl, issued Sept. 15, 1959, or otherappropriate upper roll and upper chock block counterbalancing devicesare used on the mill illustrated in order for the upper rolls and chockblocks to follow the upward movements of the upper screw downs andremain in contact therewith during adjustments thereto.

As indicated in FIGS. 1 and 2, in order to assist in establishing theproper setting of the roll gap 38 between the work rolls 16 inaccordance with the desired gauge for the workpiece W to be rolled, apair of conventional feed screws or screw down devices 30 are disposedwithin threaded openings in the upper portion of the framework 12. Theends of the screws 30 are kept in abutting contact at 32 with the chockblock elements 26 for the upper roll 14 and screws 30 are adjustable byconventional actuating means (not shown).

In the rolling mill illustrated, the chock blocks 26 associated with theends of the lower backup roll 14 are interconnected to the lower portionof the framework 10 by conventional fluid actuators or pushup devices 33which include pistons mounted in openings 34 and rod elements 36directly connected to the chocks 26. These fluid actuators 33 actprimarily to compensate for the spreading apart of the rolls, changes inthe preselected roll gap setting 38 between rolls 16 and mill housingstretch resulting from insertion of a workpiece W between the rolls andthe consequent rolling loads applied to the rolls by a workpiece Wduring rolling. In their operation, devices 33 act in conjunction withthe mill screws 30 to bring the rOlls back to the desired roll gapsetting.

Although other tying arrangements can be used, an advantageousembodiment of the invention contemplates that the ends of the backuprolls 14 in the apparatus illustrated be interconnected to each other byextensible fluid actuators 42. The purpose of these actuators is toapply appropriate bending loads to the work rolls when needed at thesame time that appropriate pushup loads are applied to the rolls by theactuators 33.

The overall control circuit generally indicated at 20 in FIG. 2 for thefluid actuators 42 and 33 includes improved means for fully integratingand correlating all applied bending loads with the rolling loads appliedby the workpiece W and counter-loads applied by the pushup actuators 33at any given time in order to maintain the desired roll setting gapsubstantially uniform across the full length of the work rolls wherebythe workpiece W will be rolled with the desired substantially uniformgauge across its full width.

The control circuit 20 in the embodiment of FIG. 2 includes an improvedcircuit component sensing means comprised of a gauge rod 74 and asensing device or load cell 76. Load cell 76 can be a conventionalsensing element of the type sold by Asea Electric, Inc., of SanFrancisco, Calif, under Model No. TGPUB-ZOO and under the trade namePressductor.

The load cell 76 is connected to a hydraulic circuit for selectivelycontrolling the admittance of fluid under pressure to the fluidactuators or pushups 33 for expanding or collapsing the pushup devicesin a manner to be described more fully hereinafter. The hydrauliccircuit includes a pump 56 connected by a conduit 51 to a source ofsupply or reservoir 55. Branch lines 50 and 52 lead from main line 51 tothe various actuators 33. In the event of build-up of excess pressurefluid within the actuators 33 and conduits 50 and 52, control valves 66,connected to each conduit 50 and 52, can be preset whereby theyautomatically function to exit the excess fluid through the line 57 tothe reservoir 55.

Also included in the overall control circuit 20 is a further hydrauliccircuit for controlling the admittance of fluid under pressure to thefluid actuators 42 for applying the desired bending loads to the backuprolls 14 and in turn to the work rolls. Each fluid actuator 42 caninclude a fluid cylinder 44 within which a piston 45 is slidablydisposed. The exposed end of the rod for piston 45 as well as one end ofthe cylinder 44 can be provided with apertured enlargements 46 withinwhich the journal ends of the rolls 14 can be disposed as shown in FIG.2. Thus, the cylinder 44 can be affixed to one backup roll and thepiston 45 to the other backup roll. A pump 64 is used to supply fluidunder pressure to opposite sides of the piston 45 disposed within thecylinder 44. This pump supplies fluid under pressure from a source ofsupply or reservoir 58 through a main conduit 63 to an appropriatecontrol valve 80. Valve 80 operates to distribute fluid under pressureto either side of the pistons 45 disposed within the cylinders 44 by theinterconnected branch conduits 60 and 62, which lead to the free sidesof the pistons 45 and by the other interconnected branch conduits 65 and67 which lead to the rod sides of the pistons 45 in accordance withspecific roll bending requirements. Control valve 80 can also be presetdepending upon the requirements for fluid under pressure to either sideof the pistons 45 within the cylinders 44 of the actuators 42, to exitany excess fluid through the exhaust line 69 to the reservoir 58.

Control valves 66 for actuators 33 operate in response to appropriateelectrical signals transmitted through the lead lines 68 and generatedby their respective separate summing amplifiers 70. Suitably calibratedmeans such as an adjustable rheostat device 72 is connected to each ofthe amplifiers 70 for feeding the appropriate reference signal into theinput side of an amplifier 70.

Each set of electrical elements or electrically responsive elements 66,70 and 72 is separately connected to one of the fluid actuators 33. Ifdesired, the rheostat devices 72 of both sets of elements can bemechanically interlocked together, as schematically shown in dottedlines in FIGS. 2 and 3, whereby adjustment of one rheostat device 72will automatically cause a corresponding adjustment of the otherrheostat 72.

A brief discussion is believed to be in order at this point of how therheostats 72 act in conjunction with load cells 76 and pushups 33 alongwith screws 30 in the operational set up and working of the mill. Insetting up the mill stand for normal operation and with the mill standbeing empty of a workpiece, the fluid actuators 33 are first actuatedwhereby they will raise the lower work roll 16 and backup roll 14 to thepoint where the bottom tips of the rods 74 for the load cells 76 arebrought into contact with the chock blocks 26 for the lower backup roll14. This may be referred to as the step of preloading the load cells 76.This preloading of the load cells is, in the case of any given millinstallation, determined by the rolling requirements for the mill andthe particular load cell used. Thus, in the present instance a load cell76 may, for example, require a 20,000 lb. load to be applied thereto inorder to place it in the desired preloaded condition. At this time, rods74 are in the desired physical and pressure contact with lower chocks26. This preloading of cells 76 is accomplished by the rheostats 72which are calibrated in terms of pushup loads or load pounds, and oncethey have been set to the above 20,000 lb. load for the mill standillustrated, they will for all practical purposes require no furtherattention. When fully set, rheostats transmit the proper referencesignals to amplifiers 70 which operate valves 66 so that the actuators33 are motivated to raise lower chocks 26 to the point where they arebrought into proper pressure contact with rods 74 connected to loadcells 76. After preloading of the load cells 76, the mill operator nextadjusts screws 30 and the jack rams (not shown) to bring the upperbackup and upper work rolls down until they are properly spaced theappropriate amounts from lower backup and lower work rolls to give theproper gap setting 38 for a given rolling condition, say .055".

When a workpiece is later inserted between the work rolls and the rollsare forced apart, it will be observed that the desired pressure contactwill be lost between the load cell rods 74 and lower chock blocks 26thereby causing the load cells 76 to become unloaded. As the cellsbecome unloaded, they transmit appropriate feed back signals toamplifier 70 which then compares these signals with those from rheostats72. The difference in signals causes amplifiers 70 to signal valves 66to actuate the pushups 33 and raise rolls 14 and 16 upwardly and lowerchocks 26 back to the point Where they are again in the proper pressurecontact with rods 74 for the load cells 76, thereby reestablishing theproper loading of the load cell 76 to the point (cg. 20,000 lbs.) wherecells 76 discontinue the feedback signals to amplifiers 70 and bringabout a deactivation of actuators 33.

Put another way, the normal operation of the load cell 76, rheostats 72and actuators 33 can be expressed in terms of a conventional rollingmill formula used when load cell devices 76 are incorporated in a millstand. Normal pushup loads (P), i.e. the final loads to be applied byactuator devices 33 in compensating for the final rolling loads appliedto the rolls including that of the workpiece that passes therethroughand spreads the rolls apart and for reestablishing the loading of theload cells 76, is equal to the load cell load (LC) plus the finalrolling load. Thus, (P)=(LC)+(RL).

Thus, in the above formula, if a load cell 76 as manufactured andinstalled is set to operate at a load cell load (LC) of 20,000 lbs. andthe rheostats 72 are set at the 20,000 lbs. and the rolling load (RL)including that applied by the workpiece to the rolls as it is introducedinto the mill which results in roll separation equals 180,000 lbs., thefinal pushup loads that must be applied to restore the load cells 76 totheir balanced or loaded condition and the roll gap 38 to say the abovementioned .055" would be 200,000 lbs.

In order to efliciently perform the aforesaid operations, the load cellsensing elements 76, there being one of these elements on each side ofthe mill stand 10, are connected to the vertically disposed andlaterally spaced gauge rods 74 positioned within each window 13 of theframework 12 adjacent the journal ends of the rolls 14 and 16. The upperends of the gauge rods 74 are disposed preferably immediately adjacentthe lower surface portion to the frame 12, while their lower ends, whichare preferably rounded off, rest upon and have the desired floatingpressure contact with the upper surfaces of the chock blocks 26associated with the lower backup roll 14. To facilitate vertically freebut laterally restrained movement of each gauge rod 74 and loading andunloading of the cells 76, the rods 74 are passed through appropriatevertically disposed passageways in upper chock blocks 26 and 28 andlower chock block 28. These passageways are indicated by the dottedlines 77 in FIGS. 1 and 2. Due to this mounting arrangement, movementsof the upper chocks 26 and 2-8 during initial screw down operations willhave no effect on cells 76.

Although it is to be understood that a pair of active sensing devices 76can be mounted on each side of the mill in the upper portion of theframe 12 for engagement with the upper ends of the rods 74 in eachwindow 13, only one active sensing device 76 need be used for each sideof the mill stand in actual practice.

In some instances, it may also be desirable to use a dummy or followerrod 74 in combination with a fully operative sensing rod 74 in eachwindow and with one end of the dummy rod resting on the lower chock 26and with its upper end contacting the undersurface of the frame 12. Insuch instances, the dummy or follower rods can act as vertical guidesfor the lower chock block 26 upon which the operative sensing rod 74rests so that the lower block will be restrained and cannot take onsimultaneous twisting movements about the axis of the rolls.

Each sensing element 76 is electrically connected to one of theamplifiers 70 by a line 77 (see FIG. 2) and operates in response toappropriate pressures exerted by contact with a lower chock 26 throughits associated gauge rod 74 to transmit appropriate feed back signals toits associated amplifier 70 when deviations occur in the 20,000 lb.pushup loads as determined by the original reference signal beingtransmitted through rheostats 72, all as noted above. The signalstransmitted by a sensing element 76 are opposite in polarity to theinitial 20,000 lbs. reference signals transmitted from the rheostats 72to the amplifiers 70. Whenever the feed back signals from cells 76 tothe summing amplifiers 70 are in effect substantially cancelled out bythe signals being transmitted to the amplifiers by the preset rheostats72, either during the initial start up with no workpiece W between therolls or during rolling when the gap 38 has exceeded the desired gaugesetting, valves 66 will cease operating and stop the further flow ofpressure fluid into the bottom sides of fluid actuators 33. This signalcancellation as noted above occurs at the time the pushup loads from theactuators 33 have loaded the cells 76 at the requisite (LC) load of20,000 lbs. or at the time sensing rods 74 are in the appropriatepressure contact with the lower chocks 26.

By the contact pressure mounting of the sensing gauge rods 74 in themanner aforedescribed, the rods and in turn cells 76 are not adverselyinfluenced in their operation by external loads imposed thereon, such asby the weight of rolls or the chock blocks or by any torque of the feedscrews whereby inaccurate or non-reliable feed back signals could betransmitted to the amplifiers 70 by the sensing elements 76. Thus, thesensing devices 76 perform their roll separation and rolling loaddetection functions through the medium of amplifiers 70, etc. in anextremely sensitive and highly reliable fashion and efliciently operatethe compensating pushups 33.

The electrical components of circuit 20 used to operate and control theroll bending actuators will now be described. Main control valve 80 iselectrically connected to a summing amplifier 76 by line 78 whereby,depending upon the type of signal received from the amplifier 76', thecontrol valve operates to direct fluid under pressure from pump 64through the proper branch conduits 65 and 67 or 60 and 62 to the varioussides of the pistons to effect bending of the backup rolls and in turnthe work rolls in the fashion desired.

Excess fluid from the supply conduit 63 or fluid returned from thevarious sides of cylinders 44 by the conduits and 62 or 65 and 67 as thecase may be is at the same time directed by the valve 80 through theconduit 69 to the reservoir 58. An adjustable rheostat 74 calibrated inthe appropriate roll bending load pounds is also connected to the inputside of the summing amplifier 76' and is manipulated at the proper timeby the mill stand operator to transmit the appropriate roll bendingreference signal thereto. The amplifier 76 then continues thetransmission of this signal through line 78 to the valve 80 and valve 80operates to cause admittance of selected amounts of fluid under pressureto actuators 42 so as to apply the desired bending loads to the backupand work rolls 16.

The incorporation of bending rolls in the mill stand aggravates theproblem of maintaining the desired roll gap 38 at say the above .055"across the length of the rolls since the application of the roll bendingloads will increase the rolling loads (RL) and apply additional forceson the pushup actuators 33 which must be compensated for. This meansthen if the overall mill compensation is to be obtained, operation ofthe roll bending and pushup devices must also be fully correlated andsynchronized with each other if the pushups are to continue to performtheir proper function.

This correlation has been effected in the instant invention by way of aunique interlock or integration of the various pushup and bending rollcomponents in the overall circuit 20. This component interlock involvesuse of an auxiliary summing amplifier 86 and suitable load feed backsensing devices 82, 88, and 92, all of which can be of the type whichtranslate or convert a given fluid pressure at any given time into anappropriate electrical signal. These sensing devices 82, 88, 90 and 92can be of the type sold by Computer Instrument Corporation of New Yorkunder Model No. 3000. The sensing devices 88 and 90 are disposed withinthe branch conduits of the pushup actuator fluid circuit immediatelyadjacent the pushup devices 33 as shown in FIG. 1. The other sensingdevices are both disposed within the branch conduit 60 of the rollbending fluid circuit for constantly sensing the fluid pressure withinthe roll bending actuators 42. Sensing devices 88 and 90 are bothelectrically connected by their separate output lines 89 to the inputside of the auxiliary summing amplifier 86. Sensing device 92 islikewise connected by its output line 91 to the input side of amplifier86 and output line 84 connects the remaining sensing device 82 to theinput side of the summing amplifier 76'. A rheostat 94 is alsoelectrically connected across the output of amplifier 86 to the inputside of amplifier 76'.

When no workpiece W is in the mill and with the initial pushup loadsetting preset at 20,000 lbs. by initial adjustment of the rheostats 72in the manner aforedescribed, the output signal from amplifier 76' canbe such as to normally produce no actuation of valve 80 and noapplication of bending loads to the rolls 1-6 and 14. When, however, aworkpiece is passed through the mill and a roll bending operation isrequired for any reason, such as roll heat up, etc. to reestablish thedesired roll contour for rolling, the operator moves rheostat 74 to theproper roll bending load application position.

In the case of where a constant roll bending load is to be applied, theoperator merely adjusts rheostat 74,

leaving the other rheostat 94 in the circuit between am plifiers 86 and76' in a zero or at rest position. By turning this roll bend pressureadjusting rheostat 74 to increase pressures in actuators 42, a positivesignal is fed to the roll bending summing amplifier 76' and if nocountersignal is fed back from the roll bending pressure sensor 82 thesignal to valve 80 will continue to be positive until valve 80 has fullyoperated to build up the necessary pressures in actuators 42. As thepressure builds up, the pressure sensor 82 will feed back negativesignals to summing amplifier 76' or signals opposite in polarity to thesignals set by rheostat 74. When the signals from rheostat 74' aresubstantially equated with the signals from sensor 82, the signals fromamplifier 76' to the valve 80 will cease and shut off valve 80 when thedesired roll bending pressure is reached.

An increase in roll bending cylinder pressure, however, will also causethe additional application of pressure on the pushup cylinders thus, ineffect, increasing the rolling load which will relieve the pressure onthe load cells as contact is lost between rods 74 and the lower chockblocks 26. This loss of pressure on the load cells will result in theunloading of the load cells and cause the signals from the load cells 76to amplifiers 70 to be appropriately negative. The signals thenemanating from amplifiers 70 as determined by the difference betweenload cell signals and rheostats 72 will cause whatever increase in thepushup cylinder pressure is needed to reload cells 76 and compensate forthe roll bending pressure and the mill housing stretch due to the newincrease in rolling load.

This additional pushup loading will, however, usually cause undesirableroll deflection from the bending deflection desired which will now bereflected by feed back signals from sensors 82 and 92 and, consequently,may require additional roll bending to compensate for the increase inpushup loading.

This is done automatically in the following fashion. It will beremembered that auxiliary summing amplifier 86 receives feed backsignals both from pushup load sensors 88 and 90 and a roll bending loadsensor 92. The feed back signal in line 91 from sensor 92 is opposite inpolarity to the signals from the pushup sensors in lines 89 and thisfeed back signal reflects the loss in the desired bending roll pressuresas set by rheostat 74'. All of these signals are new combined with oneanother at amplifier 86 and the algebraic sum of the two sets ofsignals, which are properly calibrated as regards each other inamplifier 86, is used as a further signal that can be fed to amplifier76' and this further signal is superimposed upon the original signaltransmitted through amplifier 76 and as initially received from rheostat74. It will also be remembered that roll bending sensor 82 continues tooperate at the same time and when the feed back signals from line 84coming from bending roll sensor 82, which are opposite in polarity tothe net input signals received by amplifier 76' from rheostat 74 andamplifier 86, substantially reaches the value of the aforesaid net inputsignals activation of valve 80 will cease and the desired balancebetween bending roll actuators and pushup actuators will be reached. Inthe aforesaid operation of amplifier 86, the algebraic sum of thesignals from sensors 88 and 90 and 92 can be regarded as amounting tothe final or overall rolling load, (i.e. bending load plus thesuperimposed workpiece load) plus the contant preset load cell pressure,which final rolling load is to be equated by the final pushup loads.

Thus, any increase in the overall rolling load will be followedinstantly by the required pushup pressures and pushup loads. If furthercompensating bending loads are required they too are made readilyavailable. In order to keep the aforesaid process from cascading, sinceit must be remembered that load cells 76 are also functioning at thesame time to maintain load cell pressure, until both the roll bendpressure and the pushup pressure are at the maximum, preferably not morethan 50 percent of the differential pushup pressure signals fromamplifier 86 are fed to the roll bending summing amplifier 76'. This isaccomplished by means of the rheostat 94 interposed in the circuitbetween amplifiers 86 and 76'. Rheostat 94, of course, can be adjustedto increase or even further decrease the signals from amplifier 86 or tomake other minute adjustments in the feed to amplifier 76'. Theseamplifiers 70, 76' and 86 can be of the type sold by Burr-Brown ResearchCorporation of Tucson, Ariz., as Model Nos. 1506 or 1507. Instead ofrheostat 94, a suitable function generating device can be employed,which can be made to vary the effect of amplifier 86 with relation toany desirable variable, such as rolling load, temperature of work rolls,etc.

In the modified form of the control circuit 57 of FIG.

3, in which parts corresponding to previously described parts are usedand given the same reference numerals unless otherwise specified, it iscontemplated that the gauge rods 74 and load cells 76 would be removedfrom the mill 10 of FIGS. 1 and 2. Thus, with the rolls 14 and 16 beingso disposed relative to each other within the mill 10 whereby for allpractical purposes there is no gap between the rolls 16 and prior toentrance of a workpiece therebetween, the modified circuit of FIG. 3 isadjusted in such a fashion by adjustments of rheostats 72 so as to applya predetermined pushup load on the backup and work rolls in accordancewith expected rolling load conditions and established rolling practices.This preselected pushup load setting can then be used as a mainreference point for operation of the modified overall control circuit 57of FIG. 3.

Thus, in the instance of control circuit 57, the sensing devices 88' and90', which are similar to sensing devices 88 and 90 previouslydescribed, are used to constantly sense or monitor the fluid pressure ofthe pushup components in the overall circuit 57. They are eachadvantageously connected in parallel by their separate lines 96 to theauxiliary summing amplifier 86 as before and in addition to differentones of the two summing amplifiers 70. The sensing device 92, which issimilar to device 92, within the roll bending load component part ofcircuit 57 is not only connected by the line 98 to the amplifier 86 inthe roll bending load part of the circuit as before, but it is alsoconnected and interlocked in parallel to one of the summing amplifiers70 in the pushup load portion of the circuit. The other sensing device82, which is similar to previously described sensing device 82, and islocated within the bending load component part of the circuit, is notonly electrically connected by the line 100 to an amplifier 76' in theroll bending portion of the circuit as before, but it is also connectedand interlocked by the same line 100 to the other summing amplifier 70in the pushup load portion of the circuit. The electrical signalstransmitted by the roll bend load feed back sensing devices 82' and 92'are normally of the same polarity as the initiating pushup signalsreceived from the rheostat load setting devices 72 but opposite inpolarity to the signals normally received from the feed back sensingdevices 88 and 90' used in sensing the fluid pressures in the lines forthe pushup actuators 33.

By virtu of the aforesaid interlocking of the several sensing devices88', 90', 82 and 92', the signals from rheostats 72 are used as followsto set the pushup actuators to a given pressure position so that thedesired roll gap will be established and maintained during a givenrolling operation. When additional pushup pressures are needed tocompensate for the rolling load applied to the rolls by a workpiece W,the feed back signals from sensors 88 and 90 transmitted to amplifiers70 reflect this and amplifiers. 70 will operate to produce the necessary actuation of valves 66 until the signals from sensors 88 and 90 areagain substantially equated with the signals from rheostats 72. If theaforesaid rolling load is further increased by operation of the rollbending actuators 42 so that a new overall rolling load exists, sensors82 and 92' in addition to feeding back signals to the main roll bendingload amplifier 76' also feed back signals to the summing amplifiers 70along with feed back signals from sensors 88 and 90 until the algebraicsum of the feed back signals of the sensors 88, 90" and sensors 82' and92' substantially equate the original signals fed to amplifiers by thepresetting of amplifiers 70 by rheostats 72' and thereby indirectlyreestablish the desired roll gap setting as determined by the originalpresetting of rheostats 72.

Conversely, if the pushup pressures at any time become so great wherebythe signals to amplifier 76' become unbalanced and applied roll bendingloads and roll contour are adversely affected, the feed back signalsfrom pushup sensors 88 and 90' t0 amplifier 86 are further compared withthe feed back signal from sensor 92' which reflects the change in rollbending pressure from that desired and being requested by rheostat 74.When the algebraic sum of the signals from sensors 88', 90' and 92' andas transmitted by amplifier 86 substantially equate the feed back signalfrom sensor 82 to amplifier 76', no differentiating signal will betransmitted to amplifier 76 from amplifier 86 for further operatingvalve 80 and the roll bending load will be retained at that establishedby the setting of rheostat 74. Thus, sensors 92' and 82' in the circuitof FIG. 3 as in the case of sensors 92 and 82 in the circuit of FIG. 2perform a dual function in that they act as feed back devices for theroll bending actuators and at the same time as a means for comparingpushup pressures with bending roll pressures whereby any increase inpushup pressure which is adverse to the desired bending roll pressuresis compensated for by increasing the roll bending pressures untilthedesired balance or proper equilibrium is established between rollbending and pushup pressures.

Further, the various embodiments of the instant invention can be used toadvantage with other rolling mill instrumentations, such as speciallydesigned work flattening control devices, computers, etc., to obtain thevery optimum overall rolling conditions such as Where one mill standequipped with the improvements of the instant invention is used aloneand equipped with specially designed work flattening control devices ora series with other mill stands equipped with specially designed Wor-kflattening control devices. The invention is also applicable to millstands comprised only of work rolls which have roll bending attachmentsand to mills used to roll other materials besides metal.

Advantageous embodiments of the invention have been shown and described.It is obvious to those skilled in the art that various changes andmodifications may be made therein without departing from the spirit andscope thereof, as set forth in the appended claims, wherein:

What is claimed is:

1. In a rolling mill apparatus including a framework and a pair of rollsrotatably and slidably mounted within said framework; a mill roll gapcontrol system for said apparatus comprised of a roll pushup meansincluding a first actuator operatively connected to said frame work andone of the rolls for applying selected pushup loads to said rolls and afirst fluid circuit for said first actuator; a roll bending meansincluding a second actuator operatively connected to a roll for applyingbending loads thereto and a second independent fluid circuit for saidsecond actuator; a first control means for controlling said first fluidcircuit and for operating the actuator of said roll pushup means; asecond control means for controlling said second fluid circuit and foroperating the actuator of said roll bending means; means includingelectro-load sensing means interlocking said first and second controlmeans, said first and second fluid circuit and said first and secondactuators in an interdependent relationship whereby a predeterminedactuation of one of said actuators can produce a preselected actuationof the other actuator in order to reestablish and maintain anestablished roll gap setting.

2. The apparatus as set forth in claim 1, including means for presettingone of said control means in order to initially establish apredetermined roll gap setting for a given rolling operation.

3. A mill roll gap control system for use with a rolling mill apparatuscomprised of a framework, a pair of rolls and chock 'block means forrotatably and slidably mounting said rolls within said framework; saidmill roll gap control system being comprised of a pushup means includinga first actuator operatively connected to said framework and one of saidrolls for applying selected pushup loads to said rolls in a directiontransverse to the normal axis of said rolls; a first electro-controlmeans operatively connected to said first actuator and includingelectrical signal transmitting means for adjusting said first actuatorin accordance with an initially established roll gap setting when rollseparating forces generated by a workpiece being rolled are applied tosaid rolls so as to reestablish and maintain the initially establishedroll gap setting; roll bending means, and a second electro-control meansfor said roll bending means and including an electrical signaltransmitting means for adjusting the roll bending means in accordancewith a desired roll bending condition;-and further electro-control meanswhich operate in conjunction with said first and second electricalsignal transmitting means of said first and second electro-control meansto interlock said first and second electro-control means and to transmitelectrical signals to said second actuator to effect adjustment in theroll bending means when the roll bending means is adversely affected byoperation of said pushup means so as to maintain the initiallyestablished roll gap setting and there-by produce a final workpiecehaving a substantially uniform gauge across its entire width.

4. An integrated roll bending and roll pushup control system for arolling :mill apparatus comprised of a framework and a pair of rollsrotatably and slidably mounted within said framework; said controlsystem comprising a roll pushup means including a first actuatoroperatively connected to said framework and one of the rolls forestablishing and maintaining a predetermined pushup load upon said rollsand a first fluid circuit for said first actuator; a roll bending meansincluding a second actuator op eratively connected to a roll forapplying bending loads thereto and a second independent fluid circuitfor said second actuator; a first electro-control means for operatingthe fluid circuit for said pushup means; a second electrocontrol meansfor operating the fluid circuit for said roll bending means; meansincluding electro-load sensin g means interlockingsaid first and secondelectro-control means and said actuators in an interdependentrelationship whereby Whenever .a predetermined actuation of one of saidactuators adversely affects the operation of the other actuator saidother actuator will be further operated so as to bring one actuator intofull balance with the other actuator.

5. A control system as set forth in claim 4 including means forpresetting said first control means in accordance with a predeterminedpushup load.

6. A system as set forth in claim 4, wherein the first electro-controlmeans of said system includes a gauge rod and a load cell sensingelement operatively connected to said pushup means.

7. A system as set forth in claim 4, wherein chock blocks are providedfor one of the rolls and the first electro-control means of said systemincludes a gauge rod and a load cell sensing element operativelyconnected to said pushup means, the free end of the gauge rod beingmounted so as to rest upon and be in selected pressure contact with oneof said roll chock blocks whereby it is sensitive to a movement of saidroll chock block in a direction generally normal to the axis of saidchock block. I

8. A system as set forth in claim 4, wherein the rolling mill apparatuswith which the system is associated includes backup and work rolls andsaid roll bending means is connected to the backup rolls.

9. A system as set forth in claim 4, wherein said electro-load sensingmeans includes a load feed back sensor for the first fluid circuit, aload feed back sensor for the second fluid circuit and an auxiliarysumming amplifier connected to both of said load feed back sensors andto the actuator of said roll bending means.

10. A system as set forth in claim 4, wherein said electro-load sensingmeans includes an amplifier connected to said pushup means actuator, aload feed back sensor connected to said amplifier and to the rollbending means actuator, and a load feed back sensor also connected tosaid amplifier and said pushup means actuator.

11. A system as set forth in claim 4, wherein said electro-load sensingmeans includes a summing amplifier,

a load feed back sensor for the first fluid circuit, a load feed backsensor for the second fluid circuit and an auxiliary summing amplifierconnected to both of said load sensors and to said summing amplifier.

12. A system as set forth in claim 4, wherein said electro-load sensingmeans includes a first summing amplifier connected to said pushup meansactuator and a second summing amplifier connected to said roll bendingmeans actuator, a load feed back sensor connected to said first namedactuator and both of said summing amplifiers and a second load feed backsensor connected to said second named actuator and both of said summingamplifiers.

13. A system as set forth in claim 10, including means for transmittingan initial reference signal to said amplifier.

14. A system as set forth in claim 11 including means for transmittingan initial reference signal to said summing amplifier.

15. A rolling mill apparatus comprising a framework, a pair of rolls,chock blocks for rotatably and slidably mounting said rolls 'within saidframework, pushup means including an actuator operatively connected tosaid framework and one of the chock blocks for applying pushup loads toone of said chock blocks and said rolls in a direction transverse to thenormal axis of said rolls, control means operatively connected to saidpushup means actuator and including a load cell for transmittingelectrical signals to said pushup means actuator, a load cell rodconnected to said load cell and having a free end adapted to rest uponand be in pressure contact with the top of the lowermost chock block ofsaid chock blocks, said load cell rod also being mounted so as to befree of any pressure contact with another choc-k block, means forapplying a predetermined pressure to said pushup means actuator andmeans interconnecting said load cell to said actuator pressure applyingmeans whereby when a rolling load is applied to said mill apparatus by aworkpiece and the load cell rods cease to be in pressure contact withthe one chock block said load cell will operate to transmit a signal tothe actuator pressure applying means of said pushup means actuator tomove the said one chock block and return said one chock block into aselected pressure contact with the load cell rod.

16. An apparatus as set forth in claim 15 wherein said control meansincludes a summing amplifier for establishing a preselected load on saidpushup means actuator and a feed back circuit from the load cell to thesumming amplifier.

17. An apparatus as set forth in claim 15 wherein said control meansincludes a summing amplifier connected to said push-up means actuator, arheostat for establishing a reference signal to said summing amplifierand a feed back circuit from the load cell to the summing amplifier.

References Cited UNITED STATES PATENTS 3,171,305 3/1965 Stone 72-2413,250,105 5/ 1966 Stone 72240 3,280,610 10/ 1966 Qualey 72-245 3,318,1245/ 196 7 Plaisted 72-8 3,327,508 6/ 1967 Brown 7 26 FOREIGN PATENTS 747,347 4/ 1956 Great Britain.

CHARLES W. LANHAM, Primary Examiner.

A. RUDERMAN, Assistant Examiner.

US. Cl. X.R. 72-2l, 240, 245

1. IN A ROLLING MILL APPARATUS INCLUDING A FRAMEWORK AND A PAIR OF ROLLSROTATABLY AND SLIDABLY MOUNTED WITHIN SAID FRAMEWORK; A MILL ROLL GAPCONTROL SYSTEM FOR SAID APPARATUS COMPRISED OF A ROLL PUSHUP MEANSINCLUDING A FIRST ACTUATOR OPERATIVELY CONNECTED TO SAID FRAME WORK ANDONE OF THE ROLLS FOR APPLYING SELECTED PUSHUP LOADS TO SAID ROLLS AND AFIRST FLUID CIRCUIT FOR SAID FIRST ACTUATOR; A ROLL BENDING MEANSINCLUDING A SECOND ACTUATOR OPERATIVELY CONNECTED TO A ROLL FOR APPLYINGBENDING LOADS THERETO AND A SEONCD INDEPENDENT FLUID CIRCUIT FOR SAIDSECOND ACTUATOR; A FIST CONTROL MEANS FOR CONTROLLING SAID FIRST FLUIDCIRCUIT AND FOR OPERTING THE ACTUATOR OF SAID ROLL PUSHUP MEANS; ASECOND CONTROL MEANS FOR CONTROLLING SAID SECOND FLUID CIRCUIT AND FOROPERATING THE ACUTATOR OF SAID ROLL BENDING MEANS; MEANS INCLUDINGELECTRO-LOAD SENSING MEANS INTERLOCKING SAID FIRST AND SECOND CONTROLMEANS, SAID FIRST AND SECOND FLUID CIRCUIT AND SAID FIRST AND SECONDACTUATORS IN AN INTERDEPENDENT RELATIONSHIP WHEREBY A PREDETERMINEDACTUATION OF ONE OF SAID ACTUATORS CAN PRODUCE A PRESELECTED ACTUATIONOF THE OTHER ACTUATOR IN ORDER TO REESTABLISH AND MAINTAIN ANESTABLISHED ROLL GAP SETTING.